WASHINGTON (Reuters) - Investigators are looking into whether or not the Islamist militants who attacked civilians with a truck and knives in London last Saturday may have been inspired in part by a U.S. cleric, European and U.S. government officials said.

The cleric, Ahmad Musa Jebril, who had been living in the Detroit area for some years, is one of several described by authorities as online propagandists who could have influenced the three attackers, said the officials, speaking on condition of anonymity.

Jebril was first identified on Sunday as a possible inspiration for the London attacks when the British Broadcasting Corporation ran an interview by its Asian Network with a former friend of one of the attackers, whom he said listened to Jebril's sermons posted on the internet.

"I have heard some of this stuff, and it's very radical," the former friend said.

"I am surprised this stuff is still on YouTube and is easily accessible," the man said. He said he had phoned a British government anti-terrorism hotline to report what he had heard and seen.

Several attempts by Reuters to find Jebril to obtain comment were unsuccessful. Jebril is a U.S. citizen of Palestinian descent.

Nobody answered several calls to a Dearborn, Michigan telephone number listed for Jebril and it did not accept voice mail messages. A lawyer who represented Jebril in an insurance fraud criminal case has retired and could not be reached for comment.

The Federal Bureau of Investigation and the U.S. Attorney's office in Detroit had no comment on Jebril's activity.

Commuters walk past floral tributes to the victims of the recent attack at London Bridge and Borough Market in central London, Britain June 7, 2017.Stefan Wermuth

Islamic State claimed responsibility for the attack by men who drove a truck into pedestrians on London Bridge and then stabbed revellers in nearby pubs, killing seven people and wounding dozens. Police shot dead three attackers.

Laith Alkhouri of Flashpoint, a private company that monitors militant internet activity, said Jebril had sent condolence messages to the family of a British militant who died fighting in 2013 in Syria, where Islamic State has lost territory in recent months.

"It comes as no surprise to me that one of the London attackers would have been listening" to Jebril, Alkhouri said.

Jebril was convicted in 2005 in Michigan for fraudulent insurance claims on properties he and his father owned.

Court documents submitted by the government at his sentencing said Jebril and his father had involvement with Islamist militant groups.

In 2014, a judge ordered restrictions on Jebril's use of computers and online access after prosecutors said he had violated conditions of his early release from prison.

The restrictions expired in 2015 and were not renewed. Jebril has not posted new Twitter messages since 2014.

The International Centre for the Study of Radicalisation at King's College in London described Jebril in a 2014 report as one of two English-speaking "spiritual authorities" who had become inspirational figures for foreigners fighting in Syria.

(This version of the story has been refiled to correct company name to Flashpoint from Flashpoint Global Partners, paragraph 10)

Reporting by Mark Hosenball in Washington; editing by John Walcott and Grant McCool